Method and apparatus for transceiving channel related to terminal that supports half duplex transmission in mobile communication system

ABSTRACT

A method and apparatus of a user equipment (UE) for transmitting and receiving data in a wireless communication system. The UE receives first time division duplex (TDD) uplink-downlink configuration information for a first cell and second TDD uplink-downlink configuration information for a second cell, determines whether a subframe in the first cell is a special subframe and the subframe in the second cell is a downlink subframe according to the first and second TDD uplink-downlink configuration information, and determine, if the subframe in the first cell is the special subframe and the subframe in the second cell is the downlink subframe, not to receive a signal on the second cell in orthogonal frequency division multiplexing (OFDM) symbols that overlaps with at least one of a guard period (GP) or uplink pilot time slot in the first cell.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 16/708,192,filed Dec. 9, 2019, now U.S. Pat. No. 11,310,823, which is acontinuation of application Ser. No. 15/796,664, filed Oct. 27, 2017,now U.S. Pat. No. 10,506,627, which is a continuation of applicationSer. No. 14/382,307, filed Aug. 29, 2014, now U.S. Pat. No. 9,832,789,which is the National Stage of International Application No.PCT/KR2013/001574, filed Feb. 27, 2013, which claims the benefit of U.S.Provisional Patent Application No. 61/604,603, filed Feb. 29, 2012, thedisclosures of which are fully incorporated herein by reference as iffully set forth herein.

BACKGROUND 1. Field

The present invention relates to a channel transmission/reception methodand apparatus of a terminal supporting half duplex transmission in amobile communication system and, in particular, to a method forcontrolling downlink transmission in a situation where the terminalssupporting the half duplex transmission are not capable of simultaneousuplink transmission and downlink reception and operate in differentmulticarrier TDD configurations.

2. Description of Related Art

An LTE system is an OFDMA-based communication system designed to supportFrequency Division Duplex (FDD) and Time Division Duplex (TDD). Also, itis designed to support half duplex transmission. The LTE system has beendesigned for the goal of supporting FDD and TTD on a single carrier inRelease 8 and then FDD and TDD on one or more carriers in Release 10under the assumption that the uplink and downlink transmissiondirections of the carriers are identical each other in TDD. In additionto those features, Release 11 aims to support the TDD system having thecarriers with uplink and downlink transmission directions different intime from each other and the design thereon is under progress.

Meanwhile, it may occur that a plurality of carriers having differentTDD configurations are aggregated such that a special subframe and adownlink subframe are scheduled simultaneously at the same subframeduration and thus the uplink part of the special subframe and thedownlink subframe conflict each other. This is likely to cause a problemto the terminal operating in the half duplex-duplex mode which cannottransmit and receive at the same time.

In the case of Physical Random Access Channel (PRACH) transmitted in theuplink part of the special subframe, its transmission timing isdetermined by the terminal and not changed by the base station'sscheduling and, if the downlink transmission is suspended at thedownlink subframe to guarantee the uplink transmission at the specialsubframe, this may cause a problem of wasting the frequency resourceeven when the terminal operates in reception mode at the downlink partof the special subframe.

SUMMARY

The present invention has been conceived to solve the above problems andaims to provide a method of transmitting/receiving channels efficientlyin the time duration where uplink and downlink transmissions collideespecially when the terminal operates in the half-duplex mode withmultiple carriers having different TDD configurations.

In accordance with an aspect of the present invention, a channeltransmission/reception method of a terminal operating in a half-duplexmode in a mobile communication system includes receiving schedulinginformation on multiple carriers with different TDD configurations froma base station, determining whether to receive a downlink channel withina subframe duration in which per-carrier subframes including at leastone special subframe coincide, and communicating channels with the basestation depending on whether the downlink channel is received.

In accordance with another aspect of the present invention, a channeltransmission/reception method of a base station for a terminal operatingin a half-duplex mode in a mobile communication system includesdetermining whether TDD configurations of multiple carriers for channeltransmission/reception are identical with each other, determining, whenthe TDD configurations differ from each other and at least one specialsubframe and at least one downlink subframe coincide in a same subframeduration, Orthogonal Frequency Division Multiplexing (OFDM) symbols foruse in downlink channel transmission in the downlink subframe dependingon whether a resource for PRACH transmission is allocated to theterminal in the special subframe, and transmitting a schedulinginformation on the multiple carriers to the terminal.

In accordance with another aspect of the present invention, a channeltransmission/reception apparatus of a terminal operating in ahalf-duplex mode in a mobile communication system includes a transceiverwhich receives scheduling information on multiple carriers withdifferent TDD configurations from a base station and communicateschannels with the base station and a controller which determines whetherto receive a downlink channel within a subframe duration in whichper-carrier subframes including at least one special subframe coincide.

In accordance with still another aspect of the present invention, achannel transmission/reception apparatus of a base station for aterminal operating in a half-duplex mode in a mobile communicationsystem includes a controller determines whether TDD configurations ofmultiple carriers for channel transmission/reception are identical witheach other and determines, when the TDD configurations differ from eachother and at least one special subframe and at least one downlinksubframe coincide in a same subframe duration, Orthogonal FrequencyDivision Multiplexing (OFDM) symbols for use in downlink channeltransmission in the downlink subframe depending on whether a resourcefor PRACH transmission is allocated to the terminal in the specialsubframe and a transceiver which transmits a scheduling information onthe multiple carriers to the terminal.

The channel transmission/reception method and apparatus of the terminaloperating in the half-duplex mode in a mobile communication systemaccording to the present invention is advantageous in terms of improvingdata transmission efficiency and avoiding simultaneous downlinkreception and uplink transmission at the terminal operating in thehalf-duplex mode in such a way of determining the presence/absence ofdownlink data channels scheduled at the same time with a specialsubframe on different carriers and, if present, the length of thedownlink data channel according to the presence/absence of PRACHtransmission of the terminal at the special subframe and the specialsubframe configuration in the system aggregation of carriers havingdifferent TDD configurations.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a configuration of an exemplarystructure of a TDD radio frame for use in LTE supporting FDD and TDD;

FIG. 2 is a diagram illustrating a detailed configuration of the specialsubframe;

FIG. 3 is a diagram illustrating a transmission format of PRACH;

FIG. 4 is a diagram illustrating a situation where a special subframeand downlink subframe coexist simultaneously;

FIG. 5 is a diagram illustrating a situation where a terminal receives adownlink channel from a base station according to the first embodimentof the present invention;

FIG. 6 is a diagram illustrating a situation where a terminal receives adownlink channel from a base station according to the second embodimentof the present invention;

FIGS. 7A and 7B are diagrams illustrating situations where the terminalreceives downlink channel from the base station according to the thirdembodiment of the present invention;

FIGS. 8A and 8B are diagrams illustrating situations where the terminalreceives downlink channel from the base station according to the fourthembodiment of the present invention;

FIG. 9 is a flowchart illustrating a procedure for the base station todetermine the scheduling information to be transmitted to the terminalfor uplink and downlink communication with the terminal according to anembodiment of the present invention;

FIG. 10 is a flowchart illustrating a procedure for the terminal toreceive the scheduling information from the base station and performuplink and downlink communication based thereon according to anembodiment of the present invention;

FIG. 11 is a block diagram illustrating a configuration of the basestation for communicating uplink and downlink channel with the terminalaccording to an embodiment of the present invention; and

FIG. 12 is a block diagram illustrating a configuration of the terminalfor communicating uplink and downlink channel with the base stationaccording to an embodiment of the present invention.

DETAILED DESCRIPTION

Exemplary embodiments of the present invention are described withreference to the accompanying drawings in detail. Detailed descriptionof well-known functions and structures incorporated herein may beomitted to avoid obscuring the subject matter of the present invention.Further, the following terms are defined in consideration of thefunctionality in the present invention, and may vary according to theintention of a user or an operator, usage, etc. Therefore, thedefinition should be made on the basis of the overall content of thepresent specification.

Although the description is directed to the OFDM-based radiocommunication system, particularly the 3GPP EUTRA, it will be understoodby those skilled in the art that the present invention can be appliedeven to other communication systems having the similar technicalbackground and channel format, with a slight modification, withoutdeparting from the spirit and scope of the present invention.

FIG. 1 is a diagram illustrating a configuration of an exemplarystructure of a TDD radio frame for use in LTE supporting FDD and TDD.One radio frame 101 spans 10 ms equal to 30720 Ts where Ts is1/(1500×2048) seconds. One radio frame consists of 10 subframes, and TDDsubframes are classified into three types, i.e. downlink subframededicated for use totally in downlink transmission, uplink subframe foruse totally in uplink transmission, and special subframe 103 for usepartially in downlink transmission and partially in uplink transmission.The special subframe is necessary for switching from downlinktransmission to uplink transmission.

The TDD radio frame has one of 7 configurations defined by the kinds ofthe 10 subframes constituting the radio frame as shown in table 1.

TABLE 1 ▪ Uplink-downlink Downlink-to-Uplink Subframe numberconfiguration Switch-point periodicity 0 1 2 3 4 5 6 7 8 9 ▪ 0 5 ms D SU U U D S U U U ▪ 1 5 ms D S U U D D S U U D ▪ 2 5 ms D S U D D D S U DD ▪ 3 10 ms  D S U U U D D D D D ▪ 4 10 ms  D S U U D D D D D D ▪ 5 10ms  D S U D D D D D D D ▪ 6 5 ms D S U U U D S U U D

In table 1, ‘D’ denotes the subframe reserved for downlink transmission,‘U’ denotes the subframe reserved for uplink transmission, and ‘S’denotes the special subframe.

FIG. 2 is a diagram illustrating a detailed configuration of the specialsubframe.

As shown in FIG. 2 , the special subframe 201 consists of DwPTS field203 for downlink control channel and data channel transmission, UpPTSfield 207 for uplink channel transmission, and Guard Period (GP) 205 forswitching from the downlink transmission to the uplink transmission andcompensating for propagation delay of the signal, and the lengths of thethree fields may vary as shown in table 2.

TABLE 2 Normal cyclic prefix in downlink Extended cyclic prefix indownlink UpPTS UpPTS Normal Extended Normal Extended Special cycliccyclic cyclic cyclic subframe prefix in prefix in prefix in prefix inconfiguration DwPTS uplink uplink DwPTS uplink uplink 0  6592 · Ts 2192· Ts 2560 · Ts  7680 · Ts 2192 · Ts 2560 · Ts 1 19760 · Ts 20480 · Ts 221952 · Ts 23040 · Ts 3 24144 · Ts 25600 · Ts 4 26336 · Ts  7680 · Ts4384 · Ts 5120 · Ts 5  6592 · Ts 4384 · Ts 5120 · Ts 20480 · Ts 6 19760· Ts 23040 · Ts 7 21952 · Ts — — — 8 24144 · Ts — — —

As shown in table 2, there are 9 kinds of special subframeconfigurations that can be selectively used per carrier or cell andnotified from the base station to the terminals.

Unlike the FDD and TDD terminals, the half-duplex terminal may use thedownlink and uplink transmission bandwidth in the same way as the FDD orTDD terminal but cannot perform transmission and receptionsimultaneously. In the LTE and LTE-A systems, whether to support thehalf-duplex transmission is determined by the base station schedulerwhich, especially in the FDD mode, controls such that downlink anduplink transmissions do not occur simultaneously on the same frequency.Since the downlink and uplink are on the same frequency band in the TDDmode, the transmission and reception do not occurs simultaneously.

Since the multiple carriers have the same TDD configuration, in Rel. 10,even in the case of using the carrier aggregation, the scheduling oftransmission and reception on the multiple carriers is performed in thesame way as before. In Rel. 11 supporting the multiple carriers withdifferent TDD configurations, however, uplink-downlink collision mayoccur at a certain subframe.

Particularly when a special subframe and a downlink subframe occur atthe same time, the uplink part of the special subframe collides withsome OFDM symbol of the downlink subframe so as to cause a problem inthat the terminal fails transmitting/receiving at the correspondingsymbols. This is the case where the terminal has the data to receivefrom the base station at the same time of attempting transmission ofPRACH at the uplink part of the special subframe. Prior to startingexplanation of an embodiment of the present invention in association ofsuch a case, a described is made of the PRACH transmission of theterminal briefly.

The terminal transmits PRACH in uplink for initial attach or uplinksynchronization. FIG. 3 is a diagram illustrating a transmission formatof PRACH. The PRACH is a signal occupying a predetermined frequencyregion and including a Cyclic Prefix (CP) 301 and a Sequence 303, andthe terminals transmit the signals with unique codes in the sequencesfor identification.

There are four preamble formats characterized by different PRACHsequence and CP lengths.

TABLE 3 Preamble format T_(cp) T_(SEQ) 0 3168 · T_(s) 24576 · T_(s) 121024 · T_(s)  24576 · T_(s) 2 6240 · T_(s) 2 · 24576 · T_(s) 3 21024 ·T_(s)  2 · 24576 · T_(s) 4  448 · T_(s)  4096 · T_(s)

In table 3, format 4 is used only in subframe type II supporting TDDand, particularly, capable of being transmitted only at the specialsubframe. The special subframe configuration supporting PRACH format 4can be used only with the configurations 5, 6, 7, and 8 for the DLnormal CP and only with configurations 4, 5, and 6 for the DL extendedCP in table 2. The special subframe may carry two types of signals inuplink, i.e. PRACH in the preamble formation 4 of table 3 and SoundingReference Signal (SRS). For PRACH transmission, the base stationdetermines only the transmission resource while the base stationdetermines the transmission timing.

As described above, in the case of aggregating the carriers havingdifferent TDD configurations (one carrier having one of the TDDconfigurations 0, 1, 2, and 6 of table 1 and the other carrier havingone of the TDD configurations 3, 4, and 5 of table 1), the specialsubframe (S) and downlink subframe (D) may be scheduled simultaneouslyat the 6th subframe as shown in table 1. As described above, since thespecial subframe has both the downlink and uplink parts, it causes aproblem at the half-duplex terminal which cannot perform transmissionand reception simultaneously.

FIG. 4 is a diagram illustrating a situation where a special subframeand downlink subframe coexist simultaneously. Referring to FIG. 4 , thecell A 410 has one of the TDD configurations 0, 1, 2, and 6 of table 1,and the cell B 420 has one of the TDD configurations 3, 4, and 5 oftable 1. Accordingly, the 6th subframe of the cell A 410 is the specialsubframe 401, and the 6th subframe of the cell B 420 is the downlinksubframe 405. Here, the cell A 410 may be the Primary Cell (PCell), andthe cell B 420 may be a Secondary Cell (SCell).

As shown in FIG. 4 , the special subframe 401 includes both the downlinkand uplink parts, the terminal operating in the half-duplex mode failsto simultaneous transmission and reception at the duration 407 where thedownlink subframe 405 of the cell B 420 and the uplink part 403 of thespecial subframe 401 of the cell A collide.

In this case, since the PRACH transmission timing is determined by theterminal, the base station cannot schedule uplink transmission at thecorresponding duration to avoid uplink-downlink collision and, ifsuspending the downlink transmission in the cell B 420 to guarantee theuplink transmission, the terminal cannot use, even when it is performingdownlink reception operation in the cell A 410, the frequency resource.

In order to solve the above problems, the terminal according to anembodiment of the present invention determines whether to performdownlink reception based on at least one of the presence/absence ofPRACH in the special subframe and special subframe configuration.Hereinafter, a description is made of the method of controlling whetherto receive downlink channel at the subframe where uplink and downlinktransmission collide in the case where a plurality of carriers havingdifferent TDD configurations are aggregated according to an embodimentof the present invention.

FIG. 5 is a diagram illustrating a situation where a terminal receives adownlink channel from a base station according to the first embodimentof the present invention. In FIG. 5 , the cell A 503 and the cell B 505use different TDD configurations in which the 6th subframe 501 of thecell A 503 is a special subframe and the 6th subframe 507 of the cell B505 is a downlink subframe.

Referring to FIG. 5 , if it is necessary for the terminal operating inthe half-duplex mode to transmit PRACH at uplink part 509 of the specialsubframe 501 of the cell A 503, the terminal receives no signal in thecell B 505 independently of the downlink transmission of the basestation in the cell B.

Accordingly, the terminal receives the signal at the downlink part(DwPTS) of the special subframe 501, switches to uplink during the GP,and transmits PRACH at the uplink part (UpPTS) 509. If there is notPRACH transmission in the special subframe 501, the terminal receivesthe downlink signal through the cell B 507.

Since the terminal determines whether to receive downlink signal in thedownlink subframe 507 coexisting with the special subframe 501 dependingon whether to transmit PRACH in the special subframe 501, it isadvantageous for the terminal to transmit PRACH always independently ofthe scheduling of the base station. If the base station has scheduleddownlink transmission in the cell B 505, downlink retransmission isperformed.

According to the first embodiment of the present invention, if nodownlink signal is received in the downlink subframe 507 coexistent withthe special subframe 501, it is advantageous in terms of solving theproblem occurring at the region 513 of the downlink subframe 507 whichcollides with the uplink part (UpPTS) of the special subframe butdisadvantageous in terms of wasting frequency resource even though it ispossible to receive downlink signal at the part 511 overlapped with thedownlink part (DwPTS) of the special subframe.

Another embodiment of the present invention proposes a method of usingthe time duration capable of receiving downlink signal in the downlinksubframe partially overlapped with the special subframe insofar aspossible.

FIG. 6 is a diagram illustrating a situation where a terminal receives adownlink channel from a base station according to the second embodimentof the present invention. The embodiment of FIG. 6 is directed to thecase of receiving downlink signal at the duration, in the downlinksubframe, corresponding to the DwPTS of the special subframeindependently of PRACH transmission of the terminal.

Referring to FIG. 6 , at the time when the special subframe 601 isconfigured in the cell A 603 and the downlink subframe 607 in the Cell B605 for the terminal operating in the half-duplex mode, the terminalreceives the downlink signals in the downlink part (DwPTS) of thespecial subframe 601 in both the cells 603 and 605 under the assumptionthat the downlink subframe 607 of the cell B 605 is configured in thesame structure as the special subframe 601 of the cell A 603 and, ifPRACH transmission is necessary, transmits the PRACH in the uplink part(UpPTS) of the cell A 603.

Here, the cell 1 603 may be the Primary Cell (PCell), and the cell B 605is the Secondary Cell (SCell). According to the second embodiment of thepresent invention as depicted in FIG. 6 , if the PCell has the specialsubframe and the SCell has the downlink subframe 607 in the samesubframe duration, the terminal does not receive any signal from thebase station in the SCell at the OFDM symbols overlapped with at leastone of the GP and UpPTS of the PCell.

As shown in FIG. 6 , in the case that the terminal operating in thehalf-duplex mode receives the special subframe 601 in the cell A 603 andthe downlink subframe 607 in the cell B 605, if the resource for PRACHtransmission is allocated to the terminal in the uplink part (UpPTS)609, the base station configures the data channel of the downlinksubframe 607 of the cell B to be coincident with the downlink part(DwPTS) of the special subframe of the cell A 603. Otherwise if no PRACHtransmission resource is configured in the uplink part (UpPTS) 609, thedata channel destined to the terminal may be transmitted in the wholedownlink subframe 607 of the cell B 605.

Accordingly in the case that it is necessary to transmit PRACH in theuplink part (UpPTS) 609 of the special subframe 601, the terminalreceives the downlink data during the downlink part (DwPTS) of thespecial subframe 601 in the cell A 601 and during the part 611 of thedownlink subframe 607 which matches the DwPTS of the special subframe601.

According to the second embodiment of the present invention, theterminal is capable of securing downlink data regions as much as thedownlink part (DwPTS) always on all the carriers so as to improve thedata transmission efficiency as compared to the first embodiment.

If the base station configures the resource for PRACH transmission inthe uplink part (UpPTS), it is necessary to match the part 611 allocatedfor downlink transmission in the downlink subframe 607 to the downlinkpart (DwPTS) of the special subframe 601, the size of the controlchannel region decreases as compared to the legacy case. This is becausethe maximum symbol size of the control channel is 2 in the specialsubframe and 3 in the downlink subframe.

In summary, in the case that the terminal operating in the half-duplexmode receives the special subframe 601 in the cell A 603 and thedownlink subframe 607 in the cell B 605, the transmitter of the terminaloperates in match with the symbol structure of the special subframe ofthe cell A 603, at least with the GP and UpPTS, so as to receive thedownlink symbols by means of the receiver of the terminal in the cell B605 within the corresponding time duration.

FIGS. 7A and 7B are diagrams illustrating situations where the terminalreceives downlink channel from the base station according to the thirdembodiment of the present invention. The embodiment of FIGS. 7A and 7Bis directed to the case where the terminal checks the schedulinginformation transmitted by the base station in downlink independently ofPRACH transmission of the terminal.

Referring to FIG. 7A, in the case that the special subframe 701 isconfigured in the cell A 703 and the downlink subframe 707 is configuredin the cell B 705 simultaneously for the terminal operating in thehalf-duplex mode, if the downlink data channel resource allocation andtransmission format, i.e. DL grant, is demodulated successfully in thedownlink subframe 707 of the cell B 705, the terminal receives the datachannel of the cell B 705 and the downlink signal in the DwPTS of thespecial subframe 701 in the cell A 703.

Otherwise if it fails to demodulate the DL grant in the downlinksubframe 707 of the cell 705, the terminal stops receiving downlinksignal in the cell B 705 but receives the downlink signal at thedownlink part (DwPTS) of the special subframe 701 of the cell A 703 and,if necessary, transmits PRACH at the uplink part (UpPTS).

According to the third embodiment of the present invention, the terminalreceives the control channel (PDCCH) in the downlink subframe of thecell B 705 at least and, if there is no DL grant transmitted by the basestation in the downlink subframe 707, receives no downlink signal in thedata region of the cell B 705. However, the terminal may receive uplinkcontrol channel of the control region of the corresponding downlinksubframe 707.

In detail, the terminal receives the control channel region 709 of thedownlink subframe 707 first and checks the scheduling information fordata channel transmission in the cell B 705. If there is no downlinkscheduling information, the terminal does not receive symbols followingthe control channel region 708 and, if necessary, transmits PRACH at theuplink part 709 of the special subframe 701. At this time, the terminalmay check the control channel for uplink transmission regardless of theexistence of the downlink scheduling information.

Referring to FIG. 7B, if the terminal receives the downlink controlchannel successfully, it receives the data channel in the whole downlinksubframe 707 of the cell B 715 and the downlink part (DwPTS) of thespecial subframe of the cell A 713 and skips transmission of PRACH atthe uplink part (UpPTS) 719 of the special subframe 711 of the cell A713.

If the base station does not permit transmission of the control channelfor downlink transmission in the downlink subframe 707 of the cell B705, the terminal may check the control channel for uplink transmissionat the control channel region (PDCCH) of the downlink subframe 707 underthe assumption that the symbols following the control channel (PDCCH) ofthe downlink subframe 707 of the cell B 705 carries no downlink signal.

In detail, assuming that the cell A 703 is the primary cell (PCell) andthe cell B 705 is the secondary cell (SCell), if it fails to demodulatethe DL grant received in the control channel region of the downlinksubframe of the SCell which is coincident with the special subframe ofthe PCell, the terminal does not receive the downlink signals such asPDSCH, E-PDCCH, PMCH, and PRS in the data channel region of the downlinkchannel region.

According to the third embodiment, the base station is capable ofscheduling the data channel freely regardless of PRACH transmission ofthe terminal, and the terminal is capable of determining whether totransmit PRACH through determination on presence/absence of schedulingso as to avoid unnecessary PRACH transmission. If the terminal needs totransmit PRACH and if the base station schedules data channeltransmission for PRACH transmission of the terminal, the PRACHtransmission may be delayed; however, since the base station does notperform scheduling any longer until the synchronization with theterminal is acquired, the terminal may secure the time for PRACHtransmission.

FIGS. 8A and 8B are diagrams illustrating situations where the terminalreceives downlink channel from the base station according to the fourthembodiment of the present invention. The embodiment of FIGS. 8A and 8Bis directed to the case of determining the downlink signal receptiontime duration according to the lengths of the downlink and uplink partswhen a plurality of special subframes with different configurations aretransmitted coincidently.

Referring to FIG. 8A, assuming that the special subframe configurationof the cell A 803 is X and the special subframe configuration of thecell B 805 is Y in association with the terminal operating in thehalf-duplex mode, the terminal determines whether the lengths of theuplink parts (UpPTS) of the special subframe configurations X and Y areidentical with each other.

If the uplink parts (UpPTS) of the two special subframes are identicalin length with each other, the terminal receives the downlink channel inthe downlink parts (DwPTS) of the respective special subframes. That is,the terminal receives the downlink channel at the downlink part (DwPTS)807 according to the special subframe configuration X in the cell A 803and at the downlink part (DwPTS) 809 according to the special subframeconfiguration Y in the cell B 805.

In the case that the uplink parts (UpPTS) of the two special subframesare identical in length with each other, it is possible, although theterminal receives the downlink channel through the longest downlink part(DwPTS), for the terminal to switch to the uplink part (UpPTS) foruplink channel transmission during the Guard Period (GP).

Referring to FIG. 8B, if the uplink parts (UpPTS) of the specialsubframe configurations X and Y are different in length from each other,the terminal performs downlink channel reception based on the specialsubframe configuration having the longest uplink part (UpPTS).

That is, if the respective special subframes appearing simultaneously inthe cell A 813 and cell B 815 are different in length from each other,the terminal receives the downlink symbols as many as the length of thedownlink part (DwPTS) 817 of the special subframe 811 of the cell A 813because the UpPTS of the special subframe 811 of the cell A 813 is thelongest one.

In the case that the special subframe configurations differ from eachother as shown in FIGS. 8A and 8B, the length of the downlink receptionpart is determined depending on whether the lengths of the UpPTSs of thespecial subframes are identical with each other so as to minimizedownlink data channel transmission efficiency degradation caused by thedifference in length between the special subframe configurations.

FIG. 9 is a flowchart illustrating a procedure for the base station todetermine the scheduling information to be transmitted to the terminalfor uplink and downlink communication with the terminal according to anembodiment of the present invention.

Referring to FIG. 9 , the base station determines whether the TDDconfigurations of the multiple carriers for use in communication withthe terminal are different from each other at step 910. An embodiment ofthe present invention is applied to the case where the TDDconfigurations are different from each other especially when the specialsubframe and downlink subframe are coincident in the same subframeduration or when the special subframes structured in differentconfigurations are coincident in the same subframe duration.

The base station allocates PRACH resource in the special subframe andcalculates a number of symbols for use in downlink transmission toperform scheduling at step 920. Particularly when the PRACH transmissionresource is allocated in the special subframe according to the secondembodiment of the present invention as described above, the base stationmay set the number of OFDM symbols of the control channel region and thedata channel region of the downlink subframe coincident with the specialsubframe in the same subframe duration to a value equal to the downlinkpart of the special subframe. If there is not downlink transmission, thenumber of symbols for downlink transmission is set to 0.

Next, the base station generates the scheduling information andtransmits the scheduling information to the terminal at step 930 andtransmits the downlink channel to the terminal and receives PRACH fromthe terminal at step 940. At this time, whether to receive PRACH isdetermined depending on whether the terminal transmits the PRACH.

FIG. 10 is a flowchart illustrating a procedure for the terminal toreceive the scheduling information from the base station and performuplink and downlink communication based thereon according to anembodiment of the present invention.

Referring to FIG. 10 , the terminal receives the scheduling informationon the multiple carriers from the base station at step 1010. Next, theterminal determines whether to transmit PRACH in the special subframe atstep 1020 and determines whether to perform downlink reception at thedownlink subframe coincident with the special subframe or othercoincident special subframes structured in different configurations inthe same subframe duration and a number of symbols for downlinkreceptions at step 1030.

In detail, if it is determined to transmit PRACH in the special subframeaccording to the first embodiment of the present invention, the terminalmay determine to not receive downlink channel in the downlink subframecoincident with the special subframe in the same subframe durationaccording to the first embodiment or may determine to receive thedownlink channel only at the OFDM symbols of the downlink subframe whichcorrespond to the downlink part of the special subframe in the samesubframe duration according to the second embodiment.

According to the third embodiment, if the DL grant is demodulatedsuccessfully in the control channel region of the downlink subframeregardless of PRACH transmission, it is possible to determine whether toreceive downlink data channel in the data channel region. In the casethat the special subframes different in configuration occur coincidentlyin the same subframe duration, it is possible to determine whether toperform downlink reception and the number of symbols therefor dependingon whether the UpPTS lengths of the special subframes are identical witheach other according to the fourth embodiment of the present invention.

According to an embodiment of the present invention, the terminalreceives the downlink channel and transmits PRACH based on thedetermination result at step 1040.

FIG. 11 is a block diagram illustrating a configuration of the basestation for communicating uplink and downlink channel with the terminalaccording to an embodiment of the present invention. Referring to FIG.11 , the base station according to an embodiment of the presentinvention includes a scheduler 1110, a controller 1120, and atransceiver 1130.

The scheduler 1110 generates the scheduling information to betransmitted to the terminal under the control of the controller 1120.Particularly when the TDD configurations of the multiple carriers aredifferent from each other, it may be possible to determine PRACHtransmission resource and the number of downlink transmission symbols inthe subframe duration in which the special subframe and the downlinksubframe occur coincidently or the special subframes different inconfiguration occur coincidently.

The transceiver 1130 transmits the generated scheduling information tothe terminal and, afterward, transmits downlink channel to the terminaland receives the PRACH from the terminal.

FIG. 12 is a block diagram illustrating a configuration of the terminalfor communicating uplink and downlink channel with the base stationaccording to an embodiment of the present invention. Referring to FIG.12 , the terminal according to an embodiment of the present inventionmay include a controller 1210 and a transceiver and operate in thehalf-duplex mode in which uplink transmission and downlink transmissioncannot be performed simultaneously.

If the transceiver receives the scheduling information transmitted bythe base station, the controller 1210 determines whether to performdownlink reception and the number of symbols therefor in the subframeduration in which the special subframe and the downlink subframe occurcoincidently or the special subframes different in configuration occurcoincidently, based on at least one of presence/absence of PRACHtransmission and a special frame configuration according to anembodiment of the present invention.

The transceiver 1220 receives the downlink channel from the base stationand transmits PRACH to the base station under the control of thecontroller 1210.

It is to be appreciated that those skilled in the art can change ormodify the embodiments without departing the technical concept of thisinvention. Accordingly, it should be understood that above-describedembodiments are essentially for illustrative purpose only but not in anyway for restriction thereto. Thus the scope of the invention should bedetermined by the appended claims and their legal equivalents ratherthan the specification, and various alterations and modifications withinthe definition and scope of the claims are included in the claims.

Although preferred embodiments of the invention have been describedusing specific terms, the specification and drawings are to be regardedin an illustrative rather than a restrictive sense in order to helpunderstand the present invention. It is obvious to those skilled in theart that various modifications and changes can be made thereto withoutdeparting from the broader spirit and scope of the invention.

What is claimed is:
 1. A method performed by a base station in awireless communication system, the method comprising: transmitting, to auser equipment (UE), first time division duplex (TDD) configurationinformation for a first cell and second TDD configuration informationfor a second cell; receiving, from the UE, a sounding reference signal(SRS) on the first cell based on the first TDD configurationinformation; and determining, based on the first TDD configurationinformation and the second TDD configuration information, not totransmit a physical downlink shared channel (PDSCH) on the second cellin a time that overlaps with a reception time of the SRS on the firstcell and in a time that overlaps with a switching time of the UE betweenan uplink and a downlink.
 2. The method of claim 1, wherein the UE isnot capable of simultaneous reception and transmission on the first celland the second cell.
 3. A method performed by a base station in awireless communication system, the method comprising: receiving, from auser equipment (UE), a sounding reference signal (SRS) on a first cell;and determining not to transmit a physical downlink shared channel(PDSCH) on a second cell in a time that overlaps with a reception timeof the SRS on the first cell and in a time that overlaps with aswitching time of the UE between an uplink and a downlink, in case thatthe UE is not capable of simultaneous reception and transmission on thefirst cell and the second cell.
 4. The method of claim 3, furthercomprising: transmitting, to the UE, first time division duplex (TDD)configuration information for the first cell and second TDDconfiguration information the second cell.
 5. A base station in awireless communication system, the base station comprising: atransceiver; and a controller configured to: receive, from a userequipment (UE) via the transceiver, sounding reference signal (SRS) on afirst cell, and determine not to transmit a physical downlink sharedchannel (PDSCH) on a second cell in a time that overlaps with areception time of the SRS on the first cell and in a time that overlapswith a switching time of the UE between an uplink and a downlink, incase that the UE is not capable of simultaneous reception and atransmission on the first cell and the second cell.
 6. The base stationof claim 5, wherein the controller is further configured to transmit, tothe UE via the transceiver, first time division duplex (TDD)configuration information for the first cell and second TDDconfiguration information for the second cell.
 7. A base station in awireless communication system, the base station comprising: atransceiver; and a controller configured to: transmit, to a userequipment (UE) via the transceiver, first time division duplex (TDD)configuration information for a first cell and second TDD configurationinformation for a second cell, receive, from the UE via the transceiver,a sounding reference signal (SRS) on the first cell based on the firstTDD configuration information, and determine, based on the first TDDconfiguration information and the second TDD configuration information,not to transmit a physical downlink shared channel (PDSCH) on the secondcell in a time that overlaps with a reception time of the SRS on thefirst cell and in a time that overlaps with a switching time of the UEbetween an uplink and a downlink.
 8. The base station of claim 7,wherein the UE is not capable of simultaneous reception and atransmission on the first cell and the second cell.